This invention relates in general to material handling equipment and, more particularly, to a material handling facility and machine for breaking up material bonded together in large lumps.
Much of the coal that is mined in this country is delivered to the user in open railway cars or barges. As it leaves the mine this coal is normally in a lump size which is easily handled by conveyors and other handling equipment at the place of consumption. However, during the long rail or barge journey the conveyances pass through rain and snow storms and the coal acquires considerable moisture. This does not present much of a problem during the spring, summer and fall, but in winter the moisture often freezes and bonds the small lumps together into large massive lumps which block and disrupt the handling equipment. For example, a large lump, will not rise along a steeply inclined belt conveyor, but instead will tumble downwardly and carry much of the smaller lumps with it. In this regard, at many coal burning installations the coal is dumped into a hopper which is located in a pit. The hopper funnels the coal onto a belt conveyor that rises steeply out of the pit and delivers the coal eventually to the area at which it is consumed. Large frozen lumps of coal also tend to lodge in restricted areas of the conveying equipment, or are lese incapable of entering such restricted areas, in which case they produce jams that disrupt the equipment.
To overcome these problems frozen coal crackers have been developed. The typical frozen coal cracker is a large machine that is mounted on a permanent foundation at the base of the receiving hopper. This machine has a large slow-turning rotor that is provided teeth which pass by a breaker bar. All coal that is dumped into the receiving hopper passes through the machine, but only during the winter does the machine serve any purpose, since it breaks the large frozen lumps into lumps that are small enough to be handled by the conveying equipment. During the warmer months the machine merely stands idle with its breaker bar backed off from the rotor so that the coal passes freely through the machine. This, however, causes unnecessary wear on the rotor, and indeed the wear caused by the free falling coal often exceeds the wear caused from breaking frozen lumps. For this reason, some operators run their coal crackers during the warmer months, merely to reduce the wear and to distribute it more evenly, but this consumes energy and certainly does not eliminate the wear.